The proposed studies will investigate some of the factors which can prevent normal development of projections involved in interhemispheric interactions, and will determine the functional consequences of such anamolous projections or cortical processing. The proposed research will focus on the role of activity-dependent mechanisms. We will eliminate information based on local correlated neural activity by producing synchrony of cortical activity (with convulsant-induced epileptiform activity) and synchrony of cortical afferents (with strobe rearing). We will use anatomical tracing methods to determine the extent to which these treatments result in the anomalous survival of immature callosal projections which are normally eliminated during development. We will use physiological methods to determine the extent to which anomalous projections are functional. The proposed studies will elucidate some of the mechanisms involved in hemispheric interactions and may also offer a valuable model for the understanding of intellectual deficits resulting from childhood epilepsy.